Hydraulic jack



Dec. 9, 1930. 1 c. STUKENBORG 1,784,553

HYDRAULI C JACK Filed July 8, 1927 f5 N w INVENTOR' @y N N Ioalls C. Stu/fenborty, l BY ATTORNEY Patented I Dec. 9, 1930 UNITED STATES PATENT OFFICE LOUIS C. STUKENBORG, OFMEMPHIS, TENNESSEE, ASSIGNOR TO OILDRA'ULIC LIFT COM- PANY, OF MEMPHIS, TENNESSEE, A CORPORATION OF DELAWARE HYDRAULIC JACK Application fua July s, 1927. serial No. 204,326.

My invention relates to hydraulic or iuid pressure actuated jacks and an object thereof resides in the provision of a jack wherein the lifting ram or piston is automatically stopped '5 at a predetermined height and is permitted merous manually and automatically operable Acontrol valves now employed with mechanisms of this type. V

With the preceding vand other objects and advantages in mind the invention consists in i the combination of elements, constructions, arrangements of parts, and operations to be hereinater specically referred to, claimed and illustrated in the accompanying drawings wherein Figure 1 is a view partly in vertical section and partly in elevation of a hydraulic jack embodying my invention;

Figure 2 is a fragmentary sectional view ofthe jack with the hollow piston or ram in elevated position;

Referrin to the invention in detail a cylinder 5 1s provided having heads 6 and 7 at its upper and lower ends respectively. As illustrated in Figure 2 the head 7 is provided with a pair of spaced internal flanges 8 which surround a hollow piston or ram 9 reciprocable in the cylinder.

' Suitable packing 10 is interposed between the uppermost annular flange 8 and a stuifing box gland 11 associated with the head 7 and embracing the piston.

In order to direct iluid pressure to the upper end of the ram or piston a vertically disposed conduit 12 rises centrally from the head 6, having a. fixed piston 13 threaded upon its upper end arranged in and contacting with the walls of the hollow piston 9, the fixed piston having a central outlet opening 14 and suitable packing 15.

At its lower end the conduit 12 communicates with one end of a lateral inlet passage 16 which in turn has communication with a fluid pressure supply pipe 17 through which means of a pump 18. It is proposed to lift fboth ends of the ram or piston simultaneously and for that purpose a branch passage way 19 communicating with the passage way 16 is provided in the head"6 and arranged to discharge against a circular piston head 20 of the hollow piston 9.

For the purpose of stopping the piston or ram at a predetermined height a return conduit 20 of a larger diameter than the conduit 12 extends vertically from the head 6 surrounds the conduit 12, and has its upper end attached to the under face of the piston 15.- E

A plurality yof air vents 21 is provided in the conduit 20 adjacent its upper end and a set of fluid pressure inlet openings 22 is provided below the openings 21. At its lower end the conduit 20 communicates with an outlet passage way 22 in the head 6 and leading therefrom is return pipe 23 arranged with -its outlet 24 to discharge into 'a receptacle 25. i v

A jack head 26 having channel shaped supporting members 27 to receive the wheels of a vehicle is provided at the underface of the jack head and is recessed as at 28 to receive the upper end of the piston or ram.

The'pump 18 is mounted upon a base 29 while the receptacle 25 is elevated above the' pump by supporting legs 30 rising from the 32 is -provided on the base 29 which is operatively connected with the pump by gearing 33. A check valve 34 is interposed between the supply pipe 17 and the pump 18 to prevent the return of Huid pressure to the latter while a control valve 35 is provided in the supply pipe 17 above the check valve so that when the jack is not in operation and the motor is running, the fluid pressure will be circulated from the pump to the receptacle 25.

The operation of the invention is as follows:

The pump being in operation and valve closed forces fluid pressure against the opposite ends of the hollow piston by way of the ico l conduit l2 and branch passage way 19 elevating the piston elevating its head and load. As' the head 20 passes beyond the ports 22 further upward movement of the piston is prevented by reason of the Huid pressure entering these ports 22 flowing in a downward direction through the return conduit, through the outlet passage 22 and back to the receptacle 25 by way of the return pipe 23. However, the fluid pressure escaping slower than the liquid column building up in the cylinder 6 supports the piston with its load in elevated position. To lower the ram or piston, pressure is released from the lower end thereof by opening the valve 35 permitting the piston to gravitate forcing the liquid from the cylinder upwardly through the pipe 17 returning it to the receptacle 25. It will be observed that vacuum is prevented from forming in the piston below the fixed piston 13 by reason of the air vents 21.

I claim:

1. In a lifting jack, a vertically arranged cylinder, a iuid pressure raised piston mounted therein, a iiuid holding receptacle, a continuously operating pump having communication with the receptacle, a pipe vcommunicating with the pump lhaving one end in communication with the lower end of the cylinder and its opposite end arranged to discharge into the receptacle, a manually controlled valve in the pipe between its discharge end and its point of communication with the pump, said pipe serving to conduct fluid to the cylinder to elevate the piston when the valve is closed and to discharge the Huid into the receptacle when the valve is open wherepon the piston will descend.

2. In' a lifting jack,.the combination of a vertically arranged tubular cylinder with a tubular piston therein, having a closed lower end, an opening in said closed end, an oil return pi e extending upwardly from the bottom 0 said cylinder, through said opening and into said piston, means forsupplying oil to said cylinder outside of said return pipe and an opening in said return pipe ad'- jacent the upper end thereof through which oil may flow'fromthe-interior of the cylinder into the'return pipe when the closed end of 'said piston assumes a position above said last mentioned opening.

3. In a lifting jack, the combination of a vertically arranged tubular cylinder with a tubular piston therein, having a closed lower end, an opening in said closed end, an oil return pipe extending upwardly from the bottom of said cylinder through said opening and into said piston, a head on said return pipe, a supply 'pi e communicating with the interior of said tu ular piston above said head, means for supplying oil to said cylinder outside of said return pipe and to said supply pipe, an opening in said return 

